Fuse or heat exploded link



Nov. 14, 1950 R. o. FERGUSON FUSE on HEAT EXPLODED LINK Filed Aug. '7, 1944 Patented Nov. 14, 1950 UNITED STATES PATENT OFFICE FUSE OR HEAT EXPLODED LINK Robert 0. Ferguson, Bristol, Tenn., assignor of one-half to Bristol Steel & Iron Works, Inc., Bristol, Va.-'Ienn., a corporation of "irginia Application August 7, 1944, Serial No. 548,450

10 Claims. 1

This invention relates to a safety device which may be used for a number of different purposes.

An object of the invention is to provide a fuse which is not subject to atmospheric changes.

A further important feature of the invention is to provide a fuse with a permanent protective sealing means which seals the activating agent, such as mercury, alcohol, or any other liquid which will expand when heated.

A further object of the invention is to provide a device of the above character whereby the link portion of the device may be fixed to explode at a definite predetermined temperature.

Still another object of the invention is to provide a mercury link which may form a part of an electric circuit or of a mechanical connection that will explode or break at a fixed predetermined temperature and which is not effected by chemical changes.

A further object of the invention is to provide a liquid which is capable of expanding due to heat changes and which is enclosed in an envelop that permanently seals the liquid, which envelop is capable of being fractured when the liquid reaches a certain temperature.

Other objects will appear hereinafter throughout the specification.

In the drawings:

Figure 1 discloses a top plan view of one application of the invention.

Figure 2 is a front elevation of a part of the device shown in Figure 1 with the invention applied thereto.

Figure 3 is a vertical section of one form of this invention.

Figure 4 is an enlarged detail view of the device shown in Figure 2, and

Figure 5 is a modification of the invention shown in Figure 3.

The device of the present invention may be used as a fuse. Heretofore fuses and similar devices which are adapted to break an electrical circuit when subjected to heat changes have been faulty when used over long periods of time due to the fact that the fusible element thereof is subjected to the atmosphere. Over long periods of time the fusing element may become corroded due to chemical conditions ofthe atmosphere or the element may become rusty. With the device of the present invention the element which corresponds to the fusing element i a liquid, and this liquid is enclosed within a sealed envelop of glass or other plastic material, or any other material that will break when subjected to the liquid within the envelop, when expanded by heat. Any

suitable material may be used for the envelop provided the material is capable of breaking when the liquid expands due to heating, and an envelop which hermetically seals the liquid.

The invention has been shown as applied to an alarm clock of the type illustrated in my issued Patent No. 1,892,337, granted December 27, 1932, in Figures 1, 2 and 4.

In Figures 1 to 4, therefore, the numeral l indicates a closed envelop of glass or other suitable material, For convenience the envelop will hereinafter be referred to as a glass envelop throughout the specification and claims, but it will be understood that the term glass envelop includes all materials which are capable of being used for the purpose of this invention.

Permanently attached in any suitable manner to the envelop ends are caps 2 and 4 which are provided with apertured ears 3 and 5 respectively. The glass envelop is provided with a weakened portion 6 which may take the form of a circumferential groove as shown in the several figures. The envelop is substantially completely filled with a liquid 1, such as mercury, but it is to be understood that other heat expanding liquids such as alcohol may be used in substitution of these liquids. The clock, which may be the same type of clock shown in my patent, is designated by the numeral 8. The clock is provided with a pair of bar member having bent-up portions 9 and [0. These bent-up portions are urged or biased in a direction away from each other as disclosed in my patent. The bent-up portions 9 and Ill extend through the apertures 3 and 5 of the link, as shown in Figures 1, 2 and 4. Upon the link exploding, the arms 9 and i0 spread apart in the manner as described in the patent noted above.

It will be appreciated that the link will explode or become ruptured in accordance with the expandible qualities of the expanding liquid 1. Some liquids become expanded at lower temperatures than others. Another means of regulating the temperature set-01f or rupture point is by using different materials for the envelop I, and a particularly efficacious method for setting the fuse to explode or rupture at a diiferent temperature is by regulating the depth of the groove 6. The deeper the groove 6 the less expansion will be required to break open the envelop. It will therefore be understood that by using one, or combining two or even three of these features, i. e. material of envelop, thickness of envelop or depth of envelop groove, I am able to accurately control the temperature at which the fuse will explode.

It will be apparent that the use of this fuse may have many applications, one of which is illustrated in Figures 1, 2 and 4. For instance in these figures the fuse takes the place of the fusible connection 40 in my patent and performs the same function.

In Figure 5 is disclosed another embodiment of this invention. In this figure numeral I! indicates the glass envelop. The interior of this envelop is filled with a liquid such as indicated in Figure 3, which liquid, such as mercury, is electrically conductive. Permanently attached to the ends of the envelop are caps H and Iii, provided respectively with apertured ears l2 and M. Extending through the sealed ends of the envelop are conductors i5 and I6, these conductors extend into electrical contact with the mercury or other liquid within the envelop and are conductively connected to the caps. The envelop is provided with a weakened groove it which corresponds to'the groove 6 of the other figures.

It will be understood that the device shown in Figure 5 may form part of an electric switch or any other electrical conductor, such as a wire, etc. When the link is exploded, the electrical circuit of which it is a part is, quite obviously broken.

The devices disclosed in the several figures herein may be used for a large number of different purposes including the use of the device shown in Figure 5 as a part of an electric circuit with electrical motors, switches and circuit connections. The invention may be used in place of and for the purpose of electric fuses now on the market and as a part of various electrical apparatuses. The device shown in Figure 3 may be used with various mechanical devices, an example of which is shown in my prior patent, supra. The embodiment shown in Figures 1 to 4 may also be used to connect together any two machine parts where it is desired to provide a release or separation of the parts upon the occurrenceiof excessive heat and where it is desired either to cause separation of the parts when excessive heating occurs adjacent them, or to set up an alarm under these circumstances, or both.

While I have shown a construction which desirably embodies the features of my invention, it will be understood that the description is to be construed in an illustrative sense only, and that I desire to be limited in the practice of this invention only to the extent set forth by the appended claims.

I claim:

1. A safety device, a hermetically sealed one piece, frangible envelop, a liquid capable of expanding when heated housed within said envelop, means forming part of a mechanical connection attached to said envelop, and conductor means extending through said envelop for electrically connecting said liquid with said mechanical connection, and means forming part of said safety device, for setting said device to explode, or rupture at a .predetermined temperature.

2. A safety device, a hermetically sealed one piece, frangible envelop, a liquid capable of expanding when heated housed within said envelop, means forming part of a mechanical connection attached to the ends of said envelop, and conductor means extending through said envelop for electrically connecting said liquid with said mechanical connection said envelop comprising a wall, and a portion of said wall being of greater thickness than another portion of said wall.

3. In a safety device, a hermetically sealed one piece, frangible envelop, a liquid in said envelop capable of expanding when heated, means forming part of a mechanical connection attached to said envelop, said envelop having a, weakened portion, and conductor means extending through said envelop for electrically connecting said liquid with said mechanical connection.

4. In a safety device, a hermetically 'sealed one piece, frangible envelop, a liquid in said envelop capable of expanding when heated, means forming part of a mechanical connection attached to said envelop, said envelop having a weakened portion, said weakened portion comprising a circumferential groove, and conductor means extending through said envelop for electrically connecting said liquid with said mechanical connection. I

5. In a heat exploding device, a hermetically sealed, one piece glass envelop of elongated shape and provided with ends, caps permanently attached to said ends. a liquid capable of expanding when heated within said envelop adapted to be hermeticaly sealed by said en,- velop, said envelop having a weakened portion, and conductor means extending through said envelop for electrically connecting said liquid with said mechanical connection.

6. In a heat exploding device, a hermetically sealed, one piece glass envelop of elongated shape and provided with ends, caps permanently attached to said ends, said caps having apertured ears, a liquid capable of expanding when heated within said envelop adapted to be hermetically sealed by said envelop, said envelop having a weakened portion, and conductor means extending through said envelop for electrically connecting said liquid with said mechanical connection.

7. A safety link comprising a hermetically sealed one piece envelop of frangible material, caps attached to said envelop on opposite sides thereof, a circumferential groove in said envelop between said caps, said groove comprising a kerf extending entirely around said envelop thereby providing a comparatively thin circumferential portion between-said caps, said envelop having a wall which is, except for said kerf, of substantially the same thickness, a liquid in said envelop capable of expanding when heated whereby the pressure of said liquid when expanded by heat will cause a complete separation of the parts of said envelop on the opposite sides of said grooves.

8. A safety link comprising a hermetically sealed one piece glass tube of elongated shape having ends, caps attached to said ends, a groove in said glass tube, said groove being located between said caps and providing a completely circular weakened portion of less thickness than the remainder of the tube wall thickness, the tube wall being otherwise of substantially the same thickness throughout, a liquid in said tube capable of expanding when heated whereby the pressure of said liquid when heated will cause a complete rupture and a separationof the glass tube on opposite sides of said circular weakened portion.

9. A safety link comprising a hermetically sealed envelop of frangible material, a circumferential groove in said envelop extending entirely around said envelop to form a comparatively thin circumferential portion, and a liquid in said envelop capable of expanding when heated whereby the pressure of said liquid when expanded by heat willcause a complete separation of the parts of said envelop on the opposite sides of said groove.

10. A safety link comprising a hermetically sealed one piece glass tube, a groove in said glass tube, said groove providing a completely circular weakened portion of less thickness than the remainder of the tube wall thickness, and a liquid in said tube capable of expanding when heated to cause a complete rupture and a separation 01' the glass tube on opposite sides of the circular weakened portion.

ROBERT O. FERGUSON.

6 REFERENCES I CITED The following references are of record in the file of this patent:

' UNITED I STATES PATENTS Number Name Date 739,327 Link Sept. 22, 1903 768,487 Simons Aug. 23, 1904 908,201 Burke Dec. 29. 1908 1,031,847 Harley July 9, 1912 1,816,016 Knight July 28, 1931 1,816,017 Ioepsinger July 28, 1931 1,849,551 .Praturlon Mar. 15, 1932 1,919,848 Levinson July 25, 1933 2,055,866 Jung et a1 Sept. 29. 1936 2,122,426 Knight Julv 5, 1938 

